Many homes are equipped with several television receivers located in different rooms. Also, many homes are equipped with plural sources of television signals, such as an ordinary antenna for capturing standard television broadcasts, a video cassette playback device commonly referred to as a "VCR", a video disk player, and a satellite receiver for receiving programs broadcast by earth satellites. All this contributes greatly to the convenience and enjoyment of television viewing, but also creates a substantial problem of interconnecting the television signal sources and television receivers within the home. It has been the practice heretofore to connect the signal sources with television receivers located in other rooms via cables extending between the rooms. Installation of these cables requires considerable effort and expense, and is often impractical. As more and more television receivers and television signal sources have been utilized within the home, this problem has become progressively more acute.
Efforts have been made heretofore to solve this problem by rebroadcasting signals from the various sources within a home. Thus, one device previously sold within the United States under the trademark TV GENIE incorporated a local transmitter arranged to accept television signals from a source within the home, modulate these television signals on a carrier at a standard television carrier frequency and then radiate this modulated carrier in free space. In essence, the local transmitter provided a locally broadcast standard television signal. This signal could be received by television receivers within the home utilizing an antenna at each such receiver. This approach entirely eliminated the need for wiring between the source and the remote television receiver. However, the locally broadcast signal could be received by any standard television receiver. Thus anyone outside the home but within range of the signal, such as in a neighboring home, could receive the signal. When the device was utilized with material not deemed suitable for broadcast over the public airwaves, others in the community such as children in neighboring homes could be exposed to such unacceptable programming.
Other local broadcast systems have been devised using non-standard carrier frequencies. For example, United States Federal Communications Commission Report No. 1544 of Oct. 21, 1985, and rulemaking petition RM 5193 referred to therein, describes a system wherein a television signal is locally broadcast at 902-928 MHz. Such a signal cannot be received by an ordinary television set. To permit reception, the television set is provided with a special adapter which receives the 902-928 MHz signal and converts it to a standard television carrier frequency. U.S. Pat. No. 2,508,353 discloses a frequency shifting radio relay system for uses other than local broadcasting of television signals.
However, none of these systems are truly satisfactory. In particular, frequency-shifting systems which work properly in a laboratory setting are susceptible to severe distortion of the transmitted television signal when used in actual operation within the home. Thus, prior to the present invention, there have been needs for a system which would alleviate those difficulties.